The present invention relates to a cassette containing a radiographic image converter plate on which radiographic images are stored.
On a radiographic image converter plate on which radiographic images are stored, the images are deteriorated including that the radiographic images are erased, when they are subjected to light-irradiation. Therefore, each of the radiographic image converter plates is contained in the cassette which is optically shielded against light, to be carried.
An example of the cassette will be explained with reference to FIG. 25. On case 102 in the drawing, there is formed opening 104 whose one side is open.
On the other hand, flexible radiographic image converter plate 106 is fixed on tray 108 having sufficient rigidity which is to be inserted in the case 102 through the opening 104 of the case 102.
Further, on the tray 108, there is integrally provided cap 110 which engages with the opening 104 of the case 102 and optically shields the inside of the case 102 against light.
Therefore, when the tray 108 is inserted in the case 102 through the opening 104 of the case 102, the cap 110 engages with the opening 104 of the case 102 and the inside of the case 102 is optically shielded against light.
In the cassette having the aforesaid structure, when foreign materials such as dust enter the case 102 from the outside thereof to stick to the radiographic image converter plate 106, it is difficult to discriminate between actual images and foreign materials on the image obtained through reading.
Accordingly, it is necessary to take out the tray 108 from the case 102 and to clean the inside of the case 102 and the tray 108.
However, the cap 110 and the tray 108 are structured solidly, which causes a problem that cleaning on vicinity B of a base portion of the cap 110 is difficult as shown in FIG. 26.
The invention has been achieved in view of the aforesaid problem, and its object is to provide a cassette wherein cleaning is easy.
FIG. 27 shows how the cassette in the conventional example stated above is loaded on image reading section 107. Radiographic images obtained on conversion plate 106 through radiographing are read by scanning the conversion plate 106 with a laser beam and by receiving stimulated emission emitted from the conversion plate with a photoreceptor section. As shown in FIG. 27, cap 110 is fixed on tray 108 in the conventional cassette. Therefore, even when the cap 110 is made to be close to image reading section 107, there still is caused relatively large gap d between the image reading section 107 and the conversion plate 106. When the gap d between the image reading section 107 and the conversion plate 106 is large, stimulated emission is disturbed in the course of image reading, reading accuracy for radiographic images is lowered, and image quality of images to be read is lowered, which are problems.
Further, as shown in FIG. 27, due to height h of internal projection of cap 110, an image area is narrowed by the height h, which is a problem.
An object of the invention is to make a gap formed between an image reading section and a conversion plate to be small even when a cassette is loaded on the image reading section, and thereby to prevent deterioration of accuracy for reading radiographic images and to prevent that an image area is narrowed.